Bio-retention is a process by which storm water is captured, often in an artificially created swale and then is treated to remove contaminants before returning the water to the ecosystem. Such systems have heretofore included collecting storm water in a retention area consisting of a shallow depression with a gravel interface and vegetated with plants or grasses. The storm water is filtered as it passes through the ground cover and the soil or is evaporated to remove the contaminants before the water is permitted to reach underground water returns for returning the water to above ground storage areas.